Sewage treatment plants as a potential source of microplastics in the environment: A preliminary study in Central India

The presence of microplastics in various environmental matrices is a reality. Besides, sewage treatment plants (STPs) play a crucial role in further adding to the microplastic pool of the environment, especially in water and soil resources. As conventional STPs are not primarily meant to remove microplastics, treated effluent and sludge contain a significant amount of microplastic items which are ultimately discharged into the surface water/soil. The present study investigated the role of selected STPs of Central India in contributing microplastics to the environment. Inlet, outlet, and sludge samples were collected from seven STPs and analyzed for the presence of microplastics. Microplastics were found in all samples with higher amounts in the inlet samples (3-35.5 items/L) compared to the outlet samples (2-13.5 items/L). Nevertheless, sludge samples showed the highest amount of microplastics (16-389 items/kg) for all the STPs under study. Size, shape, color, and chemical composition of microplastics was varied with considerable presence of polyethylene, polypropylene, polyethylene-terephthalate, polyvinylchloride, polystyrene, polyamide, polyacrylamide, polyester, and polyurethane. Discharge of these microplastic items in the surface water and terrestrial ecosystems may result in serious consequences for ecology and human health. Therefore, advanced technological development for effective microplastics' removal in STPs is inevitable.